A cross lamella for a light box

Abstract: The invention relates to a cross lamella for a light box, in which a plurality of cross lamellae are disposed at least substantially parallel to each other under (a) light source(s), transversely to the longitudinal direction of said box, and whereby the cross lamella is bounded by lateral boundary surfaces sloping upwards from the lower boundary edge of the lamella in a direction away from each other, said lateral boundary surfaces being interconnected near their upper edges by an upper boundary surface, in such a manner that the cross lamella is substantially triangular, seen in sectional view, and whereby the one lateral boundary surface extends upwards from the lower boundary edge of the cross lamella along a greater distance than does the other lateral boundary surface.

Description: The invention relates to a light box, in which a plurality of cross lamellae are disposed at least substantially parallel to each other under (a) light source(s), transversely to the longitudinal direction of said box, and whereby a cross lamella is bounded by lateral boundary surfaces sloping upwards from the lower boundary edge of the lamella in a direction away from each other, said lateral boundary surfaces being interconnected near their upper edges by an upper boundary surface, in such a manner that the cross lamella is substantially triangular, seen in sectional view and whereby one lateral boundary surface extends upwards from the lower boundary edge of the cross lamella along a greater distance than does the other lateral boundary surface and said cross lamellae are arranged mirror-symmetrically relative to the centre plane of the light box transverse to the longitudinal axis of the light box. WO 90/112245 shows such a structure wherein the lamella or transverse fins are arranged as pairs of single fins, with a mirror symmetrical design about a center plane from each pair. According the invention the cross lamellae are arranged with their upper boundary surfaces sloping downward in the direction towards said centre plane. In using the structure according the invention there will be obtained an even distribution of the emitted light. As a result of the different angles of incidence and exit of the light from the light source(s) achieved by altering the position of the boundary surface, also the occurrence of objectionable light reflections appears to be considerably less than is the case with the constructions that have been usual so far. A further reduction of the width of the upper boundary surface, seen in the longitudinal direction of the light box, so that an even better utitilization of the light from the light source(s) may be obtained, can be achieved when the connecting lines between the side edges of the upper boundary surface and the upper edges of the lateral boundary surfaces are both curved, whereby the centre of curvature of each connecting line is located at the side of the respective connecting line remote from the other connecting line. The invention will be explained in more detail hereafter with reference to embodiments of the construction according to the invention diagrammatically illustrated in the accompanying Figures. Figure 1 is a side view of a cross lamella according to the invention. Figure 2 is a smaller-scale cross-sectional view of a number of cross lamellae arranged in side-by-side relationship. Figure 3 is a diagrammatic view of a light box. Figure 4 is a front view of another embodiment of a cross lamella according to the invention. Figure 5 is a front view of a third embodiment of a cross lamella according to the invention. Figure 6 is a plan view of Figure 5. Figure 7 is a side view of Figure 5. The description below is based on a light box comprising one or more light sources fitted therein, in particular (a) TL-tube(s), whereby the light box, more in particular said TL-tube(s), extend(s) horizontally, although also other arrangements of such a light box will be conceivable, of course. As is diagrammatically indicated in Figure 3, a number of cross lamellae 2 extending parallel to each other are thereby provided under the light source(s) (not shown) within the light box. Each cross lamella has two lateral boundary surfaces 4 and 5, which extend upwards from a lower boundary edge 3 of the cross lamella 2 in a direction away from each other and which are curved, when seen in sectional view, more particularly said boundary surfaces 4 and 5 are parabolic. As is apparent in particular from Figure 2 the boundary surface 4 thereby extends upwards from the lower boundary edge 3 of the lamella along a greater distance than does the boundary surface 5. The upper edges of the lateral boundary surfaces 4 and 5 are interconnected by an upper boundary surface 6, which, assuming that the light box 1 is disposed horizontally as indicated above, includes an angle with the horizontal, seen in sectional view. It will be apparent that the surface of the above-described embodiment which is bounded by the upper boundary surface is thus smaller, measured in the longitudinal direction of the box, than would be the case if the boundary surface 5 were to extend upwards along the same distance as the boundary surface 4, in which case the upper edges of the two boundary surfaces 4 and 5 would be interconnected by a boundary surface extending horizontally, seen in sectional view. As already explained above this will make it possible to achieve an enhanced efficiency of the light box and the light source(s) provided therein. Because of the asymmetric shape of the lamella also the screening angle for the light emission will become asymmetric, as will be apparent from the angles æ and β indicated in Figure 2. In order to obtain an even distribution of the emitted light all the same, the lamellae 2 in the box 1 are preferably arranged mirror-symmetric with respect to the centre transverse plane of the light box 1, as illustrated for four lamellae in Figure 2. As is illustrated in more detail for the embodiment shown in Figure 4, the upper boundary surface 6 may also be curved rather than being made up of a straight surface. In order to further influence the angle at which the light is emitted the upper surface 6 may be provided with ribs extending transversely to the longitudinal direction of the lamella, substantially in the longitudinal direction of the box, therefore, and/or with perforations and/or be covered with a foil having a prismatic structure, which has a light-deflecting function. The cross lamella 2 shown in Figures 5 - 7 likewise has two lateral boundary surfaces 4 and 5, which extend upwards from a lower boundary edge 3 of the cross lamella 2 in a direction away from each other and which are preferably curved, when seen in sectional view, more particularly said boundary surfaces 4 and 5 are parabolic. The upper edges of the lateral boundary surfaces 4 and 5 are interconnected by an upper boundary surface 6, which in the usual user position includes an angle with the horizontal, as is illustrated in Figure 7. As furthermore appears in particular from Figure 6 the connecting lines 7 and 8 between the side edges of the upper boundary surface 6 and the upper edges of the lateral boundary surfaces 4 and 5 are curved in this embodiment. As furthermore appears from Figure 6 the centre of curvature of the connecting line 8 is thereby located at the side of the connecting line 8 remote from the connecting line 7. Similarly the centre of curvature of the connecting line 7 is located at the side of the connecting line 7 remote from the connecting line 8. As will furthermore be apparent from Figure 6 the width of the upper boundary surface 6 thereby gradually decreases from the ends of the cross lamella towards the centre of the cross lamella, seen in plan view. It will be apparent that as a result of lamellae thus shaped being used in a light box the non-transmitting surface formed by the upper boundary surfaces 6 will be comparatively small, so that when lamellae of this type are used in a light box less light from the light source(s) will be screened and thus the efficiency will be enhanced.

Claims: A light box, in which a plurality of cross lamellae (2) are disposed at least substantially parallel to each other under (a) light source(s), transversely to the longitudinal direction of said box, and whereby a cross lamella (2) is bounded by lateral boundary surfaces (4, 5) sloping upwards from the lower boundary edge (3) of the lamella (2) in a direction away from each other, said lateral boundary surfaces (4, 5) being interconnected near their upper edges by an upper boundary surface (6), in such a manner that the cross lamella (2) is substantially triangular, seen in sectional view, and whereby the one lateral boundary surface (4) extends upwards from the lower boundary edge (3) of the cross lamella (2) along a greater distance than does the other lateral boundary surface (5), and said cross lamellae (2) are arranged mirror-symmetrically relative to the centre plane of the light box transverse to the longitudinal axis of the light box, characterized in that the upper boundary surfaces of the cross lamellae are sloping downward in the direction towards said centre plane. A light box according to claim 1, characterized in that the lower boundary edge (3) of the cross lamella (2) extends rectilinearly. A light box according to claim 1 or 2, characterized in that the upper boundary edges of the lateral boundary surfaces (4, 5) extend parallel to the lower boundary edge (3) of the lamella (2). A light box according to claim 1 or 2, characterized in that the upper boundary edges of the lateral boundary surfaces (4, 5) are curved. A light box according to any one of the preceding claims, characterized in that the upper boundary surface (6) is provided with ribs extending in the longitudinal direction of the cross lamella (2). A light box according to any one of the preceding claims, characterized in that the upper boundary surface (6) of the cross lamella (2) is provided with perforations. A light box according to any one of the preceding claims, characterized in that the upper boundary surface (6) is covered with a foil having a prismatic structure, which has a light-deflecting function. A light box according to any one of the preceding claims, characterized in that the connecting lines (7, 8) between the side edges of the upper boundary surface (6) and the upper edges of the lateral boundary surfaces (4, 5) are both curved, whereby the centre of curvature of each connecting line (7, 8) is located at the side of the respective connecting line (7, 8) remote from the other connecting line (8, 7).

Inventors: VAN PUTTEN SIMON CORNELIS, VAN PUTTEN, SIMON CORNELIS
Applicants: VEKO PRODUCTS B V, VEKO PRODUCTS B.V.
Application year: 1994
Main classification: F21V11
IPC codes: F21V11